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Patient education: Gynecomastia (breast enlargement in men) (Beyond the Basics)

Glenn D Braunstein, MD
Bradley D Anawalt, MD
Section Editor
Alvin M Matsumoto, MD
Deputy Editor
Kathryn A Martin, MD
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Gynecomastia is a condition in which the glandular tissue in the breasts becomes enlarged in boys or men, sometimes causing discomfort or nipple tenderness. It is usually the result of a hormonal imbalance and typically occurs during infancy, adolescence, or mid to late life. Gynecomastia must be distinguished from the breast enlargement due to fat deposits seen in overweight men. The condition often goes away on its own, but treatments are available for severe or persistent cases. When gynecomastia is the result of an underlying health problem, treatment of that problem usually improves the gynecomastia as well.

Up to 70 percent of boys in early to mid-puberty experience gynecomastia because of the normal hormonal changes that occur during puberty. Gynecomastia is also common among middle-aged and older men. In this population, up to 65 percent of men are affected.


Although people tend to think of androgens (such as testosterone) as "male hormones" and estrogens as "female hormones," people of both sexes produce both types of hormones. In males, androgens are by far the predominant hormone, but small amounts of estrogen are also present. Gynecomastia can happen when the balance shifts, with an increase in estrogen or decrease in androgens. This can occur because of expected hormonal changes during puberty or aging or because of the use of certain drugs or herbal products.

The most common causes of gynecomastia in adult men that seek a medical evaluation for gynecomastia include:

Pubertal gynecomastia that does not resolve – 25 percent

Drugs – 10 to 25 percent

Unknown causes (idiopathic) – 25 percent

Puberty — Gynecomastia that occurs during puberty usually resolves without treatment within six months to two years. The condition sometimes develops between ages 10 and 12 years and most commonly occurs between ages 13 and 14 years. The condition persists beyond age 17 years in up to 20 percent of individuals.

Drugs — Many drugs have been associated with gynecomastia, including:

Spironolactone (brand name: Aldactone), a drug used to treat heart failure, high blood pressure, and several other conditions.

Ketoconazole, a drug used to treat fungal infections.

Cimetidine (brand name: Tagamet), ranitidine (brand name: Zantac), and related drugs called H2-receptor blockers. These drugs are used to treat stomach ulcers and severe heartburn.

If gynecomastia is caused by one of the drugs you take, your health care provider may recommend that you stop using the drug and might replace it with another drug that is less likely to cause the condition.

Gynecomastia occurs in up to 75 percent of men who take drugs called antiandrogens to treat prostate cancer. While these men may not be able to stop or substitute their prostate cancer treatment, they may be able to take steps to prevent gynecomastia. (See 'Prostate cancer patients' below.)

Herbal products — Gynecomastia in children has been associated with regular use of skin care products (lotions, soaps, and shampoos) containing tea tree oil and lavender oil [1]. These oils contain plant estrogens and can affect the body's hormone balance. Gynecomastia usually resolves completely after stopping the products. Soy products, such as soy milk, do not usually cause gynecomastia unless very large quantities are consumed regularly.

Treatment for HIV/AIDS — Men taking combination treatment for human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS), called highly active antiretroviral therapy (HAART), sometimes develop enlarged breasts. In most cases, this breast enlargement is due to fat redistribution, which is a side effect of the treatment. In some cases, though, true gynecomastia has been associated with HAART.

Unknown causes (idiopathic) — It is not always clear what causes gynecomastia during mid to late life. Still, as men age, blood testosterone levels tend to decline, and the hormone balance changes to a higher amount of estrogen-to-testosterone ratio. These factors probably conspire to account for most cases of "idiopathic" gynecomastia.


Gynecomastia should not be confused with pseudogynecomastia, which occurs in overweight men whose breasts enlarge because of fat deposits.

If you are a man or boy with enlarged or tender breasts, your health care provider will perform an examination to determine whether the tissue in your breasts is fatty or glandular. Glandular tissue is designed to secrete substances, such as milk or hormones, and usually has a network of ducts that can be felt.

If the provider has difficulty determining whether you have gynecomastia, he or she may recommend that you have a breast ultrasound or a mammogram, a specialized X-ray of the breast.

Laboratory tests — In certain situations, blood tests may be ordered to measure the level of hormones. Blood tests are not usually needed if the cause of the gynecomastia (eg, puberty, drugs) is identified.


The best treatment for gynecomastia depends upon its cause, duration, and severity and whether it causes pain or discomfort.

Adolescents — Because pubertal gynecomastia usually goes away on its own, treatment is not usually recommended initially. Instead, the provider will watch for changes in size for several months. In most cases, pubertal gynecomastia resolves during that time.

For boys with severe gynecomastia that is causing substantial tenderness or embarrassment, a short course of a drug called tamoxifen (sample brand name: Nolvadex) or raloxifene (brand name: Evista) may be recommended. These drugs block the effects of estrogen in the body and can reduce the size of the breasts somewhat. However, neither of these drugs is approved in the United States for the treatment of gynecomastia. Drugs may be prescribed without US Food and Drug Administration (FDA) approval, although the risks and benefits have not been studied completely.

Adult men — Treatment is not usually recommended in adult men whose gynecomastia is likely to be caused by an underlying health problem or by drugs. In these men, treating the underlying condition or stopping the problematic drug usually allows the gynecomastia to resolve.

For men with idiopathic gynecomastia that causes discomfort and lasts more than three months, a short course (three to six months) of tamoxifen or raloxifene may be recommended.

Prostate cancer patients — Gynecomastia is a common complication of hormonal treatment for prostate cancer (androgen deprivation therapy or antiandrogen monotherapy). However, there are treatment options available to prevent the development of gynecomastia, including tamoxifen and radiation therapy. (See "Patient education: Treatment for advanced prostate cancer (Beyond the Basics)".)

Tamoxifen — Tamoxifen can be taken along with the hormonal anti-prostate cancer treatment (androgen deprivation or antiandrogen monotherapy). Tamoxifen must be taken every day for the duration of antiandrogen treatment. In one study, only 8 percent of men who took an antiandrogen plus tamoxifen developed gynecomastia (compared with 68 percent of men who took the antiandrogen alone) [2].

Tamoxifen may also be given to men who develop gynecomastia while taking antiandrogens.

Radiation therapy — Treating the breasts with radiation before antiandrogen treatment begins can prevent gynecomastia in some men. Radiation treatment is usually delivered in one to three sessions (similar to having an X-ray). In the study above, 34 percent of men who had radiation treatment before antiandrogen therapy developed gynecomastia [2].

Gynecomastia that has already developed can be treated with higher radiation doses and may improve pain. However, when given after breasts have already developed, radiation is not very effective at reducing breast size.

Radiation therapy versus tamoxifen — Although tamoxifen is more effective than radiation for men who take antiandrogen monotherapy, tamoxifen must be taken for the duration of antiandrogen therapy. For some men, taking one to three sessions of radiation therapy is more convenient.

Surgery — Although tamoxifen and raloxifene are effective for men and boys who have had enlarged breasts for a few months, the drug is not effective in men whose breast tissue is not tender or who have had the condition for more than one year. For these men, surgery is an option to reduce the size of the breasts. For adolescents, surgery is generally not recommended until puberty is completed; there might be regrowth of the breast tissue if the surgery is performed before puberty is completed.

The extent of surgery depends upon the severity of the breast enlargement and whether there is also excess fatty tissue. Many men are treated with a combination of surgical removal of the glandular tissue and liposuction.

More extensive cosmetic surgery, including partial surgical removal of the breast skin, is required for men with more severe breast enlargement or those who have excessive sagging of the breast tissue that might occur after weight loss.


Gynecomastia in adolescent boys is usually caused by puberty-related hormonal changes. Pubertal gynecomastia usually resolves on its own, but the condition persists into adulthood in up to 20 percent of individuals. In extreme or painful cases, a brief course of tamoxifen might be recommended.

Gynecomastia in adult men may be caused by an underlying health problem or by the use of a drug. In such cases, treating the underlying condition or stopping the drug usually allows gynecomastia to resolve. When the cause of gynecomastia cannot be identified, brief use of tamoxifen may be recommended.

Men who have had gynecomastia for more than one year do not typically benefit from the use of tamoxifen. For them, surgery to reduce the size of the breasts is an option.

Men with prostate cancer who undergo antiandrogen therapy are at risk for developing gynecomastia. Pretreatment with radiation or taking a medication (tamoxifen) along with the antiandrogen are two options for preventing breast growth.


Your health care provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our website (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for health care professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient education: When men develop breasts (gynecomastia) (The Basics)
Patient education: Androgen replacement in men (The Basics)
Patient education: Low testosterone in men (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: Treatment for advanced prostate cancer (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Clinical features, diagnosis, and evaluation of gynecomastia in adults
Epidemiology, pathophysiology, and causes of gynecomastia
Management of gynecomastia
Side effects of androgen deprivation therapy

The following organizations also provide reliable health information.

National Library of Medicine

(www.nlm.nih.gov/MEDLINEPLUS/ency/article/003165.htm, also available in Spanish)

American Society of Plastic Surgeons


Hormone Health Network



Literature review current through: Nov 2017. | This topic last updated: Fri Feb 10 00:00:00 GMT 2017.
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